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From Wikipedia, the free encyclopedia
Gene expression profiling refers to the determination of the profile of transcribed genes within a cell, thus being a function of genomic responses to events and general functioning. The set of all RNA molecules in the cell (called the transcriptome) can be determined by a variety of newer techniques, such as high-throughput sequencing, or the presence of individual genes can be determined through older techniques such as Northern blotting and real-time polymerase chain reaction.
Gene expression profiling is particularly useful in adjunction with genomic sequencing, to determine what genes are actually active at different times, since although the gene information may be encoded in the genome, analysis of the transcriptome informs researchers of what genes are active, based on the promoters and inhibitors microenvironments. Furthermore, proteomic analysis is of particular importance when coupled to transcriptomic analysis, since even though genes may be transcribed, modifications at the translation levels may prevent genes from being activately translated into proteins, or may be upregulated comparatively to other genes, even with comparable amounts of mRNA transcripts.
As mRNAs can be very short lived and directly active (e.g. in the suprachiasmatic nucleus clock machinery genes), gene expression profiling must be conducted with carefully considered conditions and appropriate controls. Gene expression profiling can be qualitative or quantitative based on the method used, thus selection of method is an important factor in determining how much information about a particular transcriptome is required.